Method for preventing plant growth



United dtates Patent 3,232,735 DIETHOD FGR PREVENTING PLANT GRUWTH Gustav Weissenherger, Zurich, Switzerland, assgnor to Monsanto Company, a corporation of Delaware No Drawing. Original application .l'an. 2, 1962, Ser, No. 163,999, now latent No. 3,129,236, dated Apr. 14, 1964. Divided and this application Sept. 6, 1963, Ser. No. 311,269 Claims priority, application Switzerland, Dec. 31, 1969, 14,662/60 8 Claims. (Cl. 712.3)

This application is a division of copending application Serial No. 163,900, filed January 2, 1962, now US. Patent No. 3,129,236.

The present invention relates to new and useful organic tin compounds, a method of making these compounds, biological toxicant compositions and the use of these con pounds as biological toxicants. These new compounds are of the general formula In this formula R, R and R" signify identical or diiferent aliphatic, araliphatic, cycloaliphatic, or aromatic hydrocarbon radicals, X is an aromatic, possibly halogen-containing hydrocarbon radical, or aromatic, possibly halogen-containing hydrocarbon radicals which are connected directly to one another or are connected by an aliphatic, araliphatic or cycloaliphatic hydrocarbon radical. The radicals attached to the tin atom as well as the radicals joining the phenols may be unsaturated. Y is a hydrogen atom, a metal a.om, preferably alkali metal atom, or another tin group RRR"Sn. The preferred new organotin compounds of the invention are those having not more than 18 carbon atoms in R, R or R"; however, for some uses organotin compounds are preferred wherein R, R or R" have not more than 8 carbon atoms.

These organotin-bis-phenolates which have been unknown until now, can be obtained in different Ways. In a generally preferred method a triorganotin oxide or a triorganotin hydroxide and a bis-phenol are heated to gether, thereby the water which is formed by the reaction is continuously removed from the reaction mixture, as by evaporation, possibly under reduced pressure, or in an azeotrope with a solvent such as, for example, benzene, toluene, xylene, cyclohexane, etc. However, water-binding agents may also be used "for this purpose. The condensation occurs according to the equation:

In another method a triorganotin halide is reacted with a monoor dialkali salt of a his-phenol, or with a hisphenol in the presence of an acid-binding agent, preferably in a solvent. The necesasry alkali salts can be prepared by methods well known in the art using alkali metals or alkali metal hydrides. Tertiary organic bases such as, for example, triethylamine, pyridine, etc., are advantageously used as acid-binding agents. This reaction proceeds according to the scheme: 2RRRSnCl+NaOX-ONa-+ RRR"SnO-X-OSnR"R'R-|-2NaCl 3,232,735 Patented Feb. 1, 1566 bce Still a further method resides in the reaction of a triorganotin alkoxylate with a bis-phenol, according to the equation:

Lower (not more than 8 carbon atoms) organotin alkoxylates such an methoxylate, ethoxylate, etc., are preferably employed in this transesterification, and the alcohol split oil, is distilled continuously from the reaction mixture which is heated conveniently at about -120 C. Known catalysts promoting the reaction may be present. Depending on the circumstances, it may be advantageous to pass nitrogen into the reaction mixture.

By using the proper stoichiometric ratio of bis-phenol to tin compound reactant only one of the two hydroxyl groups of the bis-phenol reacts with the tin compound. Such compounds are equally useful for the proposed utilization and they have a better solubility, especially when they are in the form of alkali salts. The alkali metal can originate from the reaction, if a dialkali salt of a hisphenol is reacted with half the equimolar amount of a triorganotin chloride. However, in this manner is formed, as a rule, a mixture of unsubstituted, monoand disubstituted bis-phenols or bis-phenol salts. In order to get uniform products, therefore, it is suitable to convert in the usual way, end products which have still a phenolic hydroxyl group, to the desired metal salts, especially alkali salts.

Hemi-esters of bis-phenols may also be obtained on transesterification of bis-triorganotin phenolates by the reaction of bis-phenol at higher temperatures, thereby, sometimes, it may be advantageous to work with catalysts and under exclusion of oxygen. This transesterification occurs according to the equation:

Examples of triorganotin compounds which can be reacted with bis-phenols are trimethyltin oxide, triethyltin oxide, trivinyltin oxide, tri-n-propyltin oxide, tri-iso-propyltin oxide, tripropenyltin oxide, triethynyltin oxide, triallyltin oxide, tri-n-butyltin oxide, trioctyltin oxide, trilauryltiu oxide, tri'steai'yltin oxide, trioleyltin oxide, tribenzyltin-oxide, tristyryltin oxide, tricinnamyltin oxide, triphenyltin oxide, tricyclopentyltin oxide, tricyclohexyltin oxide, tricyclohexenyltin oxide, tricyclohexadienyltin oxide, etc. in place of these, the corresponding halides or the salts of other acids, or, if available, even hydroxides can be used in the reaction. Of course, the three hydrocarbon radicals on the tin atom can also be different, i.e. be a combination of the enumerated radicals. However, the symmetrically substituted triorganotin oxides, chlorides, hydroxides and alkoxides are generally more easily obtained and are therefore, to be preferred.

All existing bis-phenols can be condensed, or reacted or transesterified with these triorganotin compounds to give novel products as defined at the beginning. Preferred bis-phenols are those having not more than 25 carbon atoms.

The phenolic hydroxyl groups may be arranged in the bis-phenols in para, ortho or meta position with respect to one another, or with respect to the ring-connecting hydrocarbon radicals. Moreover, the phenol radicals may be joined either directly, or through a carbon atom, or through a chain of carbon atoms.

Suitable bis-phenols are, for example, bis-hydroxyphenyl, dihydroxybenzenes, naphthalene diols, anthracene diols, bis-(hydroxyphenyl)-methanes, -ethanes, -oropanes, -butanes, -octanes, -cyclopentanes, -cyclohexanes, -phenylmethanes, -dipl1enylmethanes, etc.

The aliphatic, araliphatic or cycloaliphatic radicals linking the two phenols can likewise be unsaturated, as in dihy-droxystilbenes, bis-(hydroxyphenyl)-propanes, -styrenes, -cyclohexenes, etc.

The corresponding compounds which contain halogenated bis-phenols were found to be particularly effective. A halogenated bis-phenol is understood here to be a bis-phenol which contains in the aromatic ring at least one halogen atom, preferably chlorine atom. As a rule, the benzene rings show 1-4 chlorine atoms which may be arranged in the optional possible manner with regard to the phenolic hydroxyl groups. Compounds derived from 2,2'-dihydroxy-5,5-dichlorodiphenylmethane or 2,2-dihydroxy 3,5,6,3,5',6 hexachlorodiphenylmethane and corresponding to the formulae C1 C1 C1 C1 C1 C1 I l l 1 l 031113;; OSIQR: C1 OSDR: Cl 7 OSHR3 have been found to be particularly active.

' The novel compounds serve as bacteri'cide, fungicide, plant protecting agent, herbicides, insecticides, etc. For these purposes, they can be converted to emulsions or mixed with fillers in conventional manner.

EXAMPLE 1 Percent Calcd Found C 32. 8 32. 86 H- 4. 6 4. 56 Sn. 36. 1 36. Cl 21. 57 21. 59

EXAMPLE 2 35.7 g. of tributyl-tin oxide (0.06 mol) and 14.9 g. of tetrachlorohydroquinone (0.06 mol) are refluxed in 230 ml. of benzene and the water formed in the reaction is azeotropically distilled oil from the reaction mixture. The reaction is complete after 2 hours. After the benzene has been distilled off a clear liquid product remains, having a refractive index of 11 1.5414.

Analysis;

Percent Cale'd Found C 43. 6 43. 67 H- 6. 54 6. 65 C 17.18 17. O0 Sn 28.70 28.30

EXAMPLE 3 By the same process as in Example 2, using 17.9 g. of tributyltin oxide (0.03 mol) and 12.2 g. of 2,2dihydroxy- 3,5,6,3',5',6'-hexachlorodiphenylmethane, a clear liquid condensation product is obtained quantitatively, having a refractive index of H 1.5638. The amount of water released corresponds to the theory.

4 Analysis:

Percent Calcd Found C 45.12 45.4 H- 5.24 5.75 5.1 24.2 2&2

EXAMPLE 4 By the same process as in Example 2, using 17.9 g. of

tributyltin oxide (0.03 mol) and 8.1 g. of 2,2'-dihydroxy- 5,5'-dichlorodiphenyhnethane (0.03 mol) in 150 ml. of toluene, a clear liquid condensation product is obtained quantitatively showing a refractive index of 11 1.5430. The amount of water which is split oil corresponds to the theory.

EXAMPLE 5 18.3 g. of triphenyltinhydroxide (0.05 mol) and 6.2 g. of tetrachlorohydroquinone (0.025 mol) are refluxed in ml. of benzene or toluene. The Water formed is azeotropically distilled off from the reaction mixture. The reaction is complete after 1 /2 -2 hours and the product formed precipitates partly during the condensation. The desired product remains quantitatively upon distillation of the solvent. The substance can be purified by recrystallization from toluene; Ml. 215-216 C.

Analysis.-Percent Sn calcd. 25.1. Percent Sn found 24.8.

EXAMPLE 6 in this example the pre-emergent herbicidal ratings of some of the organotin compounds of this invention were determined in greenhouse tests in which a specific number of seeds of 12 different plants, each representing a principal botanical type, were planted in greenhouse flats. A good grade of top soil was placed in either 9 /2 x 5%" x 2% or 9" x 13" x 2" aluminum pans and compacted to a depth of 78 inch from the top of the pan. On top of the soil were placed five seeds of each of radish, morning glory, and tomato; 10 seeds of each of sugar beet, sorghum, and brome grass; 20 seeds of each of wild buckwheat, giant foxtail, rye grass, Wild oat; approximately 20 to 30 (a volume measure) of each of pigweed and crab grass; and either 2 or 3 seeds of soybean. The seeds were arranged with three soybean seeds across the center of the large aluminum pan, the monocotyledon or grass seeds scattered randomly over the remaining one-third of the soil surface, and the dicotyledon or broadleaf seeds scattered randomly over the remaining one-third of the soil surface at the other end of the pan. The seeds were then covered with /8 inch of prepared soil mixture and the pan leveled. The herbicidal composition was applied to the plantings prior to the watering of the seeds. This application of the herbicidal composition was made by spraying the surface of the soil with an acetone solution containing a sufiicient quantity of the candidate chemical to obtain the desired rate per acre on the soil surface. The watering of the seeds was accomplished by placing the aluminum pans in a sand bench having one-half inch depth of water thereon and permitting the soil in the pans to absorb moisture through the perforated bottom of the pans.

The planted pans were thereafter placed on a wet sand bench in a greenhouse and maintained there for 14 days under ordinary conditions of sunlight and watering. At the end of this time, the plants were observed and the results recorded by counting the number of plants of each species which germinated and grew. The herbicidal rating was obtained by means of a fixed scale based on the average percent germination of each seed lot. The herbicidal ratings are defined as follows:

0--No phytotoxicity lSlight phytotoxicity 2-Moderate phytotoxicity 3-Severe phytotoxicity The pro-emergent herbicidal activity of some of the organotin compounds of this invention are recorded in Table 1 for various application rates of the organotin compounds. In Table 1, the various seeds are represented .by letters as follows:

' 5 ,agentmix, and sufiicient water to make a volume of- 6 ml. The emulsifyingagent was a mixture comprising 35 wt. percent butylamine ,dodecylbenzene sulfonate and 65 wt. percent. oft-.a tall oil-ethylene oxide condensate having 5 7 about 6 moles of ethylene oxide per mole of tall oil. The A 'G 1. injuries to the plants were then observed 14 days later and 'BGeneral broadleaf arereported in Table 2. The herbicidal ratings recorded C-Morning glory in Table 2 have the. same meaning as stated in Example 6.

. Table 2 Compound Plant Type Con The Product of Wtrpter- A B O D E F G H I J K L M N 0 0.2143111442244441 Examplel 0.05 0 0 0 0 4 0 0 0 4 0 4 0 0 0.010.00000000000000 o.20-4.s1004t1144440 Example2 n lo o gpooooaoooooooo Emmpleii his l i If15:19:21 :1:53:31 0.5242110412244343 Examples h; 0.2 02130110401142040 0.0501130000300001200 B =2650% defoliation.

1 D- -Wild oats The herbicidal compositions of this invention are either ;EBrome grass particulate solid (i.e., dusts) or liquid concentrate com- F-Rye grass positions comprising the active ingredients and either a G Radish 30 particulate solid or liquidherbicidal adjuvant which are H-Sugar beet formulation aids or conditioning agents permitting the I.-Foxtail concentrate composition to-be readily mixed with a suit- J Crab grass able solid or liquid carrier in the field for application of K+Pigweed the active ingredient on soil or plant surfaces in a toxic LSoybean concentration in a form which enables prompt assimila- MWi1d buckwheat tion by the germinating seeds, emerging seedlings, or full N-Tomato grown plants. Thus, the herbicidal compositions of this O'Sorghum invention include not only the concentrate compositions Table 1 Compound Plant Type The Product 0i- Rate, 0 D E F G H I .T K L .M N O lbs/acre 53233333-3s03-33 Examplel 100001,110a0 00 0 0.50o0no000o00o0 ifitfifiitttitt s 52222.3.33230130 Example4 "{10000010100000 0.50000'041-00001100 The-detain Table 1. illustrates thegeneralherbicidal comprising the; activeingredient. and the herbicidal adactivity as well as the selective -herbicidalactivity=of some I, juvant but also herbicidal toxicant compositions applied of the organotin compounds of the invention. Thus these in the field comprising .the concentrate composition (i.e., organotiu mpounds a ti l l ef l in oil teriliactive ingredient plus herbicidal adjuvant). and the carrier. zation applications. As demonstratedin the examples above, quite dif- EXAMPLE 7 ferent effects can be obtained by modifying the method 0 of use. of theherbicidal composition of this invention. In thls examplesthe-contact acflvltyof some 'Thus, unusualspecificity can be achieved atlower levels jfl P Q P of thls'lnvefltlon'was d of application whereas at higher levels of application a 'mlned 19 F The-organotmjcompounds to more general herbicidal effect or soil sterilization takes testedwel'e PP 111 P Y y p place. Therefore, an. essential part of this invention is {Hens-091m'sa-me-rgliassesiiandlbl'oadleaf Plants asllsed the formulation of the herbicidal composition so as to 111 fi pl'e-emfgfimi'tests:'descfibedlill EXEIIIIPIe :permit a-uniform predetermined application of the comsame numberof seeds-of the same plants used in. Example position to the plant'environment to produce the desired 6-,.were planted-in the 9 /2" x 5%"ix 2% aluminum fl t pans-arranged the samemanner'l-with ay n s .Herbicidal 'adjuvants useful in preparing the concen infdiagonal corners as described in Example 6. After the trate,.compositions and, ther f h bi i toxiplantswere 21 days old, each aluminum pan-was sprayed vcantcompositions applied to the soil or 1. t ,-i 1 d with 6 ml. of a 0.5% concentration solution of the candiparticulatesoil or liquid extending agents .such as solvents date chemical, corresponding vto. a rate ofapproxirnately or, diluentswithin-which the active ingredient is dissolved 9 lbs., per acre. f This herbicidal solution was prepared or suspended,'wetti ng or emulsifying agents which serve from 1.5 ml; of a 2% solution of the candidate compound in providing. uniform dispersions or solutions of the ac- -in acetone; 0.2 ml. of a 3:1 cyclohexanone-emulsifying tive. ingredient in the extending agents, and adhesive agents or spreading agents which improvethe contact of the active ingredient with the soil or plant surfaces. All herbicidal compositions of this invention include at least one of the above types of herbicidal adjuvants and usually include an extending agent and a wetting or emulsifying agent.

The active'ingredient need not-be dissolved in the extending agent but may merely be dispersed or suspended in the extending agent as a suspension or. emulsion. Also, the organotin compounds may first be dissolved in a suitable organic solvent and the organic solution of the active ingredient then incorporated in water or an aqueous extending agent to form a heterogeneous dispersion. 'Examples of some suitable organic solvents for use as extending agents include hexane, benzene, toluene, acetone, cyclohexanone, methylethylketone, isopropanol, butanediol, methanol, dia-cetone alcohol, xylene, dioxane, isopropyl ether, ethylene dichloride, tetrechloroethane, hydrogenated naphthalene, solvent naphtha, petroleum fractions (e.g., those boiling almost entirely under 400 F. at atmospheric pressure and having flash points above vabout 80 F., particularly kerosene), and the like.

Solid extending agents in the form of particulate solids are very useful in the practice of the present invention. 'In using this type of extending agent, the active ingredient is either adsorbed or dispersed on or in the finely-divided solid material. Preferably the solid extending agents are not hygroscopic but are materials which render the composition permanently dry and free flowing. Suitable solid extending agents include the natural clays, such as china clays, the bentonites and the attapulgites; other minerals in natural state, such as talc, pyrophyillite, quartz,

'diatomaceous earth, fullers earth, chalk, rock prosphate,

kaolin, kieselguhr, volcanic ash, salt and sulphur; the chemically modified minerals, such as acid-Washed bentonite, precipitated calcium phosphate, precipitated calcium carbonate, calcined magnesia, and colloidal silica; and other solid materials such as powdered cork, powdered wood, and powdered pecan or walnut shells. These materials are used in finely-divided form, at least in a size range of 2040 mesh and preferably in much finer size.

The particulate solid concentrate compositions are applied in the soil by admixture at the time of application with a particulate solid carrier material. If desired, this concentrate composition can also be applied as a wettable powder using a liquid carrier material. When used by this method, a wetting agent or surface active agent is added to the concentrate composition in order to render the particulate solid extending agent wettable by water to obtain a stable aqueous dispersion or suspension suitable for use as a spray. Also, the extending agent applied as a wettable powder is used in very finely-divided form preferably in a size as small as 100 mesh or smaller.

The surface active agent, that is the wetting emulsifying, or dispersion agent, used in the herbicidal composition of this invention to serve in providing uniform dispersions of all formulation components of both liquid and dust types in both the concentrate compositions and the toxicant compositions applied, may be either anionic, cationic, or non-ionic types, including mixtures thereof. Suitable surface active agents are the organic surface active agents capable of lowering the surface tension of water and include the conventional soaps, such as the water-soluble salts of long-chain carboxylic acids; the amino soaps, such as the amine salts of long-chain carboxylic acids; the sulfonated animal, vegetable, and mineral oils; quaternary salts of high molecular weight acids; rosin soaps, such as salts of a'bietic acid; sulfuric acid salts of high molecular weight organic compounds; algin soaps; ethylene oxide condensated with fatty acids, alkyl phenols and mercaptans; and other simple and polymeric compositions having both hydrophilic and hydrophobic functions.

The herbicidal concentrate compositions of this invention ordinarily have the active ingredient and the surface is a combination of liquid extending agent and surface active agent. Preferably, the surface active agent comprises from 0.1% to 15% by weight of the total concentrate composition. The remainder of the composition is the liquid extending agent.

Use of the surface active agent is necessary in the formulation of liquid concentrate compositions in order to obtain a composition containing a sufficient concen tration of the difficultly soluble organotin compounds in the liquid extending agent. However, the liquid extending agent must be selected not only on the basis of the amount of the organotin compound dissolved but also upon the basis of the solution temperature of the total composition. Thus, in some formulations, a particular combination of solvents give a sufficiently low solvent temperature but the amount of the organotin compound dissolved or dispersed in the'mixture is insuificient and a suitable surface active agent must be selected in order that more organot-in compound can be dispersed in the composition. Preferably, the concentrate composition has a solution temperature below 0 C. although compositions having solution temperatures as high as 20 C. can be used.

The concentration of organotin compound in the particulate solid or dust concentrate composition of this invention may vary over wide ranges depending upon the nature of the solid extending agent and the intended use of the composition. Applied at very low rates in order to obtain selectivity, the concentration of the active ingredient in the dust composition may be very low and may comprise as little as 1% or less by wt. of the total dust composition. By contrast, when the dust composition is to be used for soil sterilization, it may be desirable to have a very high concentration of active ingredient and for such use the active ingredient may comprise as much as 5% to 98% by wt. of the total composition. The remainder of the composition is the herbicidal adjuvant which is usually only the particulate solid extending agent. Thus, the surface active agent is not usually required in dust concentrate compositions although it can be used if desired. However, if the dust concentrate composition is to be applied as a wettable powder, surface active agent must .be added to the concentrate composition and ordinarily the amount of surface active agent will be in the range of 0.1% to 15% by wt. of the composition.

The carrier material, used for the uniform distribution of the organotin compound in a herbicidally effective amount to inhibit the growth of either all or selected plants, may be either a. liquid or a particulate solid material. The liquid and solid extending agents used to prepare the concentrate composition may also be used as the "carrier; however, the use of these materials as a carrier is often not economical. Therefore, water is the preferred liquid carrier, both for use with the liquid concentrate composition and the wettable powder concentrate. Suitable particulate solid carriers include the particulate extending agents noted above as well as the solid fertilizers such as ammonium nitrate, urea, and superphosphate, as well as other materials in which plant organisms 'may take root and grow, such as compost, manure, humus, sand and the like. I

The liquid and dust concentrate compositions of this invention can also contain other additaments such as fertilizer and pesticides. Also, these additaments may be used as, or in combination with, the carrier materials.

The herbicidal compositions of this invention are applied to the plant systems in the conventional manner. Thus, the dust and liquid compositions may be applied to the foliage of growing plants by the use of power-dusters, broom and hand sprayers, and spray-dusters.. The compositions can also be very suitably applied from ailplanes as a dust or a. spray because. the herbicidal compositions of this invention are effective in very low dosages. In order to prevent growth of germinating seeds or emerging seedlings, the dust and liquid compositions are applied to the soil according to conventional methods, and, preferably, distributed in the soil to a depth of at least /2 inch below the soil surface. It is not absolutely necessary that the herbicidal compositions be admixed with the soil particles and these compositions can be applied merely by spraying or sprinkling onto the surface of the soil. The herbicidal compositions of this invent-ion can also be applied by addition to irrigation water supplied to the field to be treated. This method of application permits the penetration of the compositions into the soil as the water is absorbed therein. Dust compositions sprinkled on the surfaceof the soil can be distributed below the surface of the soil by the usual discing, dragging, or mixing operations.

The application of a growth-inhibiting amount or toxic amount of the organotin compound to the plant system is essential in the practice of the present invention. The exact dosage to be applied is dependent not only upon the specific organotin compound but also upon the particular plan-t species to be controlled and the stage of growth thereof as well as the part of the plant to be contacted with the toxicant. In non-selective foliage treatments, the herbicidal compositions of this invention are usually applied at a rate sufliciently to obtain from 5 to 50 lbs. of organotin compound per acre but lower or higher rates might be applied in some oases. In no-nselective pre-emergent treatments, these herbicidal compositions are usually applied at a somewhat lower rate than in foliage treatments but at a rate which is ordinarily the same general range; that is at a rate in the range of 1 to lbs. per acre. In selective preemergent applications to the soil, a dosage of from 0.5 to 5 lbs. of active ingredient per acre is usually employed but lower or higher rates may be necessary in some instances. It is believed that one skilled in the art can readily determine from this disclosure, including the examples, the optimum rate to be applied in any particular case.

The essential active ingredient of the herbicidal compositions of this invention is the organotin compound disclosed in this specification. Of course, one skilled in the art will understand that mixtures of various organotin compounds can also be used.

EXAMPLE 8 For evaluation of the hacteriostatic and fungistatic effects of these new compounds, several of these compounds were tested. These compounds were mixed in predetermined concentrations with hot sterile agar which was subsequently poured into petri dishes, cooled, and allowed to harden. Nutrient agar containing the test compounds was then inoculated with the bacteria Staphylococcus azn'ezrs and Salmonella typhosa and incubated for two days at 37 C.; and Sabourauds dextrose agar containing the test compound was inoculated with the fungus organism Aspergillus niger, and incubated for five days at 27 C. The results of these tests are reported in Table 3 in column 10.

a=aotive; i=inactive.

It is noted from an examination of the data in Table 3 that the organotin compounds of the invention are very active bacte-riosta'ts and fungistats; than concentrations in some cases were as low as one part per million of the test compounds. Usually these novel compounds will be applied as bacteriostats or fungistats at concentrations in the range of 0.0001% to 1.0%, preferably 0.001% to 0.1%, suspended, dispersed or dissolved in inert carriers.

The new compounds of this invention may be applied to microorganisms (bacteni a and fungi), the growth of which it is wished to inhibit, or they may be compounded in emulsions or in other forms in a similar manner as described for compounding the organotin compounds as henbicides.

What is claimed is:

1. A method for preventing plant growth comprising applying a growth inhibiting amount of an organotin compound of the formula RRRSnOXOY, wherein R, R and R are hydrocarbons having not more than 18 carbon atorns, X is selected from the class consisting of aromatic hydrocanbon and aromatic-ring halogenated derivatives thereof having not more than 25 oanbon atoms, and Y is a RRR"Sn group wherein R, R' and R" are as defined hereinabove.

2. A method for preventing plant growth comprising applying to soils normally supporting plant growth a growth inhibiting amount of an organotin compound of the formula wherein R, R and R" are alkyl radicals having not more than 8 carbon atoms, and n and n are integers from 0 to 4 inclusive.

3. A method for preventing plant growth comprising applying to soils normally suppontin-g plant growth a growth inhibiting amount of an organotin compound of the formula wherein R, R and R are alkyl radicals having not more than 8 carbon atoms, and n is an integer from 0 to 4.

4. A method for prewent-ing plant growth comprising applying to soils normally supporting plant growth a growth inhibiting amount of an organotin compound of the formula 1 1 1 2 5. A method for preventing plant growth comprising growth inhibiting am'ount'of an or-ganotin compound. f applying to soils norm-ally supponting plant growth a the formula growth inhibiting amount of an organotin compound of G1 G1 G1 01 die formula I I l 5 a C1 C1 I I g r 7 c1 OSn(O H )a 1 (C 119) S11OOSn(C Hu)3 OS!-1(C4H9)3' t I 3. A medshod for preventing plant. growth compris n n C1 applying to soils normally supporting plant growth a growth inhibiting amount of an organotin compound o V V the formula V i 6. A method for preventing plant growth comprising 1 31 applying to soils normally supporting plant growth a 15 growth inhibiting amount of an organotin compound of the fefimlla V fl fl sh )Sn( 4 n)a ('11 $1 References Cited by the Examiner Q FOREIGN PATENTS (Ph);SnO OSn(Ph)a 806,535 12/1958 Great Britaln. 5 E 4 835,546 5/1960 Great Britain. 7

OTHER REFERENCES Van Der Kerk et aL: J. Appl. Chem, June 4, 1954, pages 314 to 318. Y

wherein Ph is the phenyl radical.

7. A method for preventing plant growth comprising applying to soils normal-1y supporting plant growth a LEWIS GOTTS, Primary Examiner. 

1. A METHOD FOR PREVENTING PLANT GROWTH COMPRISING APPLYING A GROWTH INHIBITING AMOUNT OF AN ORGANOTIN COMPOUND OF THE FORMULA RR''R"SNO-X-OY, WHEREIN R, R'' AND R" ARE HYDROCARBONS HAVING NOT MORE THAN 18 CARBON ATOMS, X IS SELECTED FROM THE CLASS CONSISTING OF AROMATIC HYDROCARBON AND AROMATIC-RING HALOGENATED DERIVATIVES THEREOF HAVING NOT MORE THAN 25 CARBON ATOMS, AND Y IS A RR''R"SN GROUP WHEREIN R, R'' ARE AS DEFINED HEREINABOVE. 